Injection systems for internal combustion engines deliver fuel from the tank into the combustion chamber of the internal combustion engine. Such an injection system usually includes, beginning in the tank, a low-pressure system including a low-pressure pump, a fuel filter and lines followed by a high-pressure system including a high-pressure pump, fuel lines, distributor rails and fuel injectors which supply the fuel to the combustion chamber of the internal combustion engine as needed in terms of time and space.
With modern time-controlled injection systems, a control unit takes over the calculation of injection functions and the activation of fuel injectors and other actuators for regulating the system and the internal combustion engine.
To open, for example, a magnetic high-pressure injector of a direct injection system, a magnet is activated, i.e., energized, its magnetic force moving the valve needle out of its seat against a closing spring and an effective fuel pressure to open the injection cross section. To minimize the power demand, the armature may be secured with a so-called armature free path on the valve needle. If energized, the armature initially accelerates and then after a small lift, strikes against the valve needle. At the point in time of lift of the valve needle, a mechanical impulse is also acting in addition to the magnetic force. Therefore a maximum required amount of magnetic force may be established to be lower and the power demand may be reduced.
The influence of the needle dynamics here may be reduced for example by a mechatronic approach such as for example a so-called controlled valve operation. The activation times or activation durations of the fuel injectors are adjusted in the sense of regulation over the service life of a motor vehicle, for example, in a controlled valve operation. For this purpose, during and/or after the activation, signals are detected and from them the opening and closing points in time as well as the open duration of the valve needle are ascertained. Thus the actual open duration of each injector may be calculated and readjusted if necessary. DE 10 2009 002 593 A1 describes one such method for adjusting an actual open duration of a valve to a setpoint open duration.
One possibility for how a position and/or a speed may be determined with an electromagnetic actuator such as an armature including a solenoid, for example, is described in DE 10 2008 054 877 A1, for example.